Field
Example embodiments relate to steam separation systems for a nuclear boiling water reactor.
Description of Related Art
A boiling water nuclear reactor generates steam by utilizing heat generated from a core and rotates a turbine and a power generator by means of the steam. In a pressurized water nuclear reactor, cooling water separately flows into a primary cooling system circulating through the nuclear reactor, and a secondary cooling system serving as a steam generator. In the primary cooling system, high-temperature water is generated by the heat generated from the nuclear reactor core. In the secondary cooling system, water in the secondary cooling system is boiled in a heat exchanger in the steam generator to become steam, which rotates a turbine or a power generator.
Regardless of the reactor type, moisture must be removed from the steam to be supplied to the turbine. To this end, a typical reactor is provided with a plurality of steam separators, dryers and the like so as to remove water from a two-phase flow of steam and water generated in the nuclear reactor or the steam generator.
In a conventional steam separator, even if the water separated from the two-phase flow that has flowed in the steam separator is discharged outside the barrel through the water discharge pipe, most of the steam flows out from the upper part of the barrel. Therefore, if the two-phase flow stream (FS) velocity is high and/or steam separator inlet moisture content is high, the number of the minute droplets that are carried by the steam is increased, which may result in an increase in moisture carry-over. The increase in moisture carry-over increases the radioactivity levels in the plant and adversely affects outage performance. For example, liquid water droplets may transport radioactive particles from the reactor to the balance of plant (BoP). These particles may deposit in various components in the main steam line and turbine and increase the radiation exposure to reactor personnel. If the moisture carry-over levels become undesirably high, certain components of the main steam line and turbine can be adversely impacted as a result of enhanced degradation from such mechanisms such as flow accelerated corrosion leading to higher maintenance costs.